An exhaust gas purification device, wherein a hydrocarbon supply valve (15) and an exhaust gas purification catalyst (13) are disposed in an engine exhaust gas passage. The concentration of hydrocarbon flowing into the exhaust gas purification catalyst (13) is oscillated at an amplitude within a predetermined range of 200 ppm or more and with a period within a predetermined range of 5 seconds or less. When a predetermined amount or more of NOx is absorbed or may be absorbed in the exhaust gas purification catalyst (13) at this time, the concentration of the hydrocarbon flowing into the exhaust gas purification catalyst (13) is temporarily increased in order to desorb the NOx absorbed in the exhaust gas purification catalyst (13).

Exhaust gas purification device for internal-combustion engine

An exhaust emission control apparatus for an internal combustion engine includes: an exhaust gas purification catalyst arranged in an exhaust gas passage of the internal combustion engine; an air/fuel ratio sensor installed on an upstream side of the exhaust gas purification catalyst and detects an air/fuel ratio of an exhaust gas discharged from the internal combustion engine; air/fuel ratio feedback control means that performs feedback control of the air/fuel ratio based on an output of the air/fuel ratio sensor; and sensor output correcting means that corrects a shift in the output of the air/fuel ratio sensor. The sensor output correcting means is configured so as to correct a shift in the output of the air/fuel ratio sensor using a lean shift amount of the air/fuel ratio sensor output in accordance with a quantity and/or a proportion of an aldehyde included in the exhaust gas.

Exhaust emission control device for internal combustion engine

PURPOSE: To compensate offset of output voltage of exhaust gas oxygen sensor occurring in alcohol fuel of a fuel blend so as to maintain theoretical fuel/air ratio of the engine. CONSTITUTION: Output voltage of an exhaust gas oxygen sensor 44 is offset by the presence of alcohol in the fuel blend from the theoretical fuel/air ratio. A controller 10 is responsive to the metering value of intake air flow MAF, feedback signal corrected signal EGOS obtained from comparing output of the sensor 44 with a reference output, and percent methanol signal in a fuel blend, and introduces a bias value obtained based on proportional plus integral control to a feedback control of liquid fuel to the engine 28 through pulse width signal fpw. As a result, the theoretical fuel/air ratio is maintained even the sensor 44 is switched beyond the theoretical fuel/air ratio.

Jiyudeisu Emu Kaaran

Papers

Control method of fuel